Investigation on carcinoembryonic antigen (CEA) will be mostly devoted to immunization of rats with CEA of murine origin. On the basis of experiments thus far performed, we anticipate that many immunized rats will produce an immune response cross-reacting with rat CEA. Resistance of immunized animals to transplantable colonic carcinoma of rat origin will be explored. Studies on reactions between tumor-specific cell-surface antigens (TSCSA) and their antibodies will be pursued using the newly developed procedure of mixed agglutination with artificial monolayers of cells and staphylococcal protein A as an anti-globulin reagent. Antigens shared by malignant and normal allogeneic cells will be studied in mice with a primary goal of eliciting tumor immunity by immunization with normal cells. Genetics of immune response to TSCSA will be further explored using hybrids of the mouse strain C57BL and syngeneic EL-4 lymphoma cells. In addition, various co-isogenic mice will be employed. Humoral antibody response and also specific resistance to the tumor will be studied. Heterophile Paul-Bunnell antigen-antibody system will be studied in relation to infectious mononucleosis as well as lymphoma, leukemia and other malignancies. A sensitive and specific passive agglutination test with purified Paul-Bunnell antigen will be developed. Appearance of Paul-Bunnell antigen on malignant lymphoid and non-lymphoid cells as well as in sera of tumor-bearing patients will be investigated. Heterophile Hanganutziu-Deicher antigen-antibody system will be extensively explored in following the lead of the frequent occurrence of Hanganutziu-Deicher antigen in sera of tumor patients. In vitro formation of both Paul-Bunnell and Hanganutziu-Deicher antibodies in a plaque assay will be investigated. Release of normal tissue antigens from tumorous mass to the circulation will be examined with reference to a ubiquitous microsomal antigen, the Wassermann antigen and a thermostable pancreatic antigen.